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JOURNALS // Vestnik Moskovskogo Universiteta. Seriya 1. Matematika. Mekhanika // Archive

Vestnik Moskov. Univ. Ser. 1. Mat. Mekh., 2025 Number 6, Pages 68–69 (Mi vmumm4734)

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Remark on countable rectangular coverings outside of a diagonal

A. P. Kombarov

Lomonosov Moscow State University, Faculty of Mechanics and Mathematics

Abstract: It is proved that a finally compact $p$-space $X$ is metrizable if and only if the space $X^2\setminus \Delta$ has a countable rectangular open cover. A similar theorem is valid for separable $M$-spaces.

Key words: metrizability, paracompactness, paracompactness off of the diagonal, normality, normality off of the diagonal, final compactness, $p$-space, $M$-space, rectangular covers, Vietoris topology, first axiom of countability.

UDC: 515.12

Received: 20.11.2024

DOI: 10.55959/MSU0579-9368-1-66-6-10



© Steklov Math. Inst. of RAS, 2026